This invention relates to a filter apparatus using a plurality of ceramic porous filter elements, and more particularly to a filter apparatus useful for purifying water including suspended materials which were contaminated by radioactivity generated in nuclear power plants.
Component members (channel boxes, control rods and the like) used in reactors of nuclear power plants have been stored in pools filled with water. In this case, transparency of the water filled in the pools is needed in operation when the irradiated metal waste contaminated by radioactivity are immersed in the pools. In general, part of the water in the pool is always filtered and purified by a filter apparatus including sintered metal filter units.
Referring to FIG. 1, a hitherto used purification filter unit 51 includes four cylindrical sintered metal filters 52 and a filter casing 53 enclosing these filters 52. The water in the pool is supplied into an upper inlet 54 of the filter casing 53 and flows through upper portions and center passages 55 of the respective sintered metal filters 52. The water is filtered and purified during the flowing from the interior to exterior of the filters 52 and is exhausted from an outlet 56.
However, the hitherto used filter apparatus including the sintered metal filters as above described is expensive to manufacture and has a short use life. In addition, this filter apparatus is complicated in construction and heavy and has only small filtering areas. In order to eliminate any of these disadvantages, a filtering apparatus using porous ceramic bodies has been proposed in, for example, Japanese Laid-open Patent Application No. 56-148,607. In this case, however, as the porous ceramic body consists of a fired material or pottery, it is only possible to manufacture small filters, and filters having wide filtering surfaces could not be produced.